The present invention relates to surgical instruments and particularly to an improved seal arrangement for a trocar tube.
A conventional trocar assembly comprises two basic interfitting, separable components: a trocar obturator subassembly and a trocar tube subassembly. The trocar obturator subassembly includes a supporting head with an elongate obturator having a tip. The tip can be a blunt or sharpened cutting tip and the tip is sometimes provided with a protective shield. The trocar tube includes a head and a depending tube together with a sealing arrangement within the head for closing and sealing the tube when it is in position during surgery. The assembly includes the trocar obturator interfitting the trocar tube with the tip projecting from the end of the tube and, if desired, being covered by the protective shield.
In ordinary use the trocar assembly penetrates a body cavity and the trocar obturator subassembly is withdrawn leaving the trocar tube in place for introducing other instruments into the body according to the requirements of a particular medical procedure. The trocar tube is provided with a sealing arrangement to close the tube in order to maintain the gas pressure within the body cavity as required for the medical procedure.
My U.S. Pat. No 5,242,412 discloses a seal for a trocar assembly, and in the Background of the Invention, the patent describes conventional sealing arrangements for trocar tubes.
The primary task of a trocar seal is to maintain pneumoperitoneal pressure while an operating instrument is present in the trocar tube, while the instrument is being inserted or removed, and after removal. In some cases the trocar double seal within the trocar tube includes an upper seal in the form of a sealing ring and a lower sealing valve.
Surgical instruments pass through the upper and lower seals giving rise to the hazard of the instrument injuring or disturbing the proper sealing position of one of the seals particularly the lower seal within the trocar tube housing. This hazard is present in the cases of disposable as well as non-disposable trocar tubes. Non-disposable trocar tubes are intended for reuse after sterilization and the opportunity arises for gradual weakening and ultimate failure of the lower seal by reason of exposure to repeated passing of surgical instruments.
The present invention provides an improved sealing arrangement for trocars in order to guard against seal failure due to instrument manipulation through the trocar, and to provide a seal cartridge that can be replaced periodically or after each use of the trocar for a single surgical procedure.
The present invention provides an inexpensive sealing arrangement for trocars with no moving parts in either of the upper and lower seals. This results in low manufacturing cost and feasibility of disposable trocar designs.
The invention also provides for improving the operating characteristics of the valve particularly its ready-to-use capability without the need to prehydrate before use, as well as valve surface lubricity and sealing characteristics.